1. Field of the Invention
The present invention relates generally to a non-contact monitoring of a surface contour of a workpiece, and more particularly, to a system for monitoring, recording and/or controlling parameters affecting the surface contour of a metallic workpiece, such as a continuous cast slab.
2. Description of the Prior Art
In the production of metal workpieces by continuous casting techniques, molten metal is supplied to the continuous caster which forms the configuration of the metal slab. In the particular instance in which slabs are formed by the continuous caster, the desired product is one in which the surfaces thereof are of uniform flatness. When a slab is formed having surfaces which are of this ideal flatness, additional processing is not required in order to flatten the surfaces. However, when the surfaces of the slab are not uniformly flat, a remedial process can be required in order to flatten the surfaces of the slab. Such a process requires grinding of the surfaces in order to reduce protruding surfaces. This additional step not only requires additional time and expense, but also results in the loss of a certain amount of the product which becomes scrap.
As a result, attempts are made to ensure that the cast product is as flat as possible Because the temperature of the slab, or other metal workpiece, as it emerges from a continuous caster can have areas in excess of 1500 degrees Fahrenheit (8 16 degrees Centigrade), and because the workpiece is typically moving at a rate of between 32 and 45 inches per minute (81 and 114 cm/min), the unaided visual appearance often does not reveal the distortion, and accurate measurement of the surface contours of the workpiece is quite difficult. A real time, on-line display and measurement of the surface contours of the workpiece as it emerges from the continuous casting machine would be beneficial in order to alter control parameters of the machine operations to minimize surface deformities. Permanent capture of the data would provide documentation for off-line study and correlation with other operating data.
Present procedures for quantitatively determining the surface flatness of a workpiece requires the metal to be cut and a cross-section of the metal to be removed to allow measurement of the surface at a remote location. This is a time consuming and expensive procedure, and cannot be performed during on-line production of the workpiece. A simpler, albeit qualitative, measurement of the surface contours of the workpiece is more frequently performed. This involves a procedure in which plant personnel occasionally place a straight edge across a surface of a workpiece and then estimate the surface geometry of the workpiece. From this qualitative evaluation then, control and alignment parameters of the continuous caster may be altered in order to produce a workpiece of greater flatness.
A system which makes slab distortion visible and which accurately and quantitatively measures the surface contours of a metal workpiece as the workpiece emerges from the continuous caster would greatly facilitate efforts to evolve caster practices to consistently produce workpieces of maximum quality with assurance such quality can be maintained through early alert to the occurrence of deviation.
U.S. Pat. No. 4,741,621 discloses a surface inspection system for a geometric surface to detect cracks and imperfections in a combustion chamber, such as a steam boiler. A reference surface curve is compared with an actual surface curve to detect surface flaws. Laser light is split into separate beams, and each beam is incident upon the wall at a different angle to prevent shadows due to surface imperfections. The system is used to detect small, hairline cracks in a surface. U.S. Pat. No. 4,188,544 discloses a system for maximizing the amount of salable wood products from logs, particularly how to optimize subdividing of the wood log at a lumber mill. A planar light source from a laser is projected at a first angle. The intersection line on the log is detected at a second angle to generate signals related to the dispersions of the workpiece. These signals are compared and modified by second known reference signals. The modified signals are converted to processing control signals for sawing the workpiece.
It is therefore the object of the present invention to provide a system to display and quantitatively determine the surface contours of a metal workpiece.
It is a further object of the present invention to provide a system which creates a quantifiable image of the surface contours of a metal workpiece to allow real-time control of caster parameters to create workpieces of maximum quality. Preferably, the system is a non-contacting device with no moving parts which can survive in the environment about a continuous caster.